Refining of hydrocarbon with boron trifluoride

ABSTRACT

Hydrocarbon stocks containing undesirable impurities are refined by admixing between about 0.1 percent and 5 percent by weight of water with said hydrocarbon stocks and then treating said admixture with an amount of gaseous boron trifluoride in excess of that necessary for complex formation with the water. An insoluble precipitate is formed of said undesirable impurities that is readily separated from the hydrocarbon.

United States Patent [72] Inventor [21] Appl. No. [22] Filed [45]Patented [73] Assignee [54] REFINING OF HYbROCARBON WITH BORONTRIFLUORIDE 7 Claims, No Drawings [52] US. Cl 208/292 [51] lnt.Cl Clog29/02 [50] Field of Search 208/292, 249, 279, 290, 291, 208, 223, 24l254, 255, 256, I77

[56] References Cited UNITED STATES PATENTS 2,062,377 12/1936 Schneider208/241 I 2,416,465 2/l947 Axe .Q 208/254 2,495,851 1/1950 Lien et al208/241 2,602,770 7/1952 Johnson et al. 208/223 2,745,792 5/1956 Shiah208/241 2,796,387 6/1957 Schmidt 208/292 OTHER REFERENCES ChemAbstracts, 53385k, Vol. 69, Sept. 30, [968 pp. 4997 and 4998.-

Primary Examiner- Delbert E. Gantz Assistant Examiner-G. J. CrasanakisAttorneys-Jordan J. Driks, Albert L. Gazzola and John J.

Mahon ABSTRACT: Hydrocarbon stocks containing undesirable impurities arerefined by admixing between about 0.! percent and 5 percent by weight ofwater with said hydrocarbon stocks and then treating said admixture withan amount of gaseous boron trifluoride in excess of that necessary forcomplex formation with the water. An insoluble precipitate is formed ofsaid undesirable impurities that is readily separated from thehydrocarbon.

REFINING F HYDROCARBON WITH BORON TRIFLUORIDE This invention relates tothe refining of mixed hydrocarbons, particularly petroleum hydrocarbons.More particularly, it relates to the refining of petroleum hydrocarbonsor'fractions of petroleum hydrocarbons containing, in addition to otherhydrocarbon compounds undesirable constituents such as organic sulfurcompounds (e.g. mercaptans, alkyl sulfides and disulfides, sulfoxides,sulfones and thiophene and its homologs), unsaturated hydrocarboncompounds, nitrogen compounds and oxygenated compounds, by treatment ofsaid hydrocarbons with boron trifiuoride and water.

Processes for treating petroleum hydrocarbons with boron trifluoride,boron fluoride hydrate and with certain boron trifluoride complexes areknown and disclosed, for example, in U.S. Pat. Nos. 2,257,627;2,416,465; 2,495,851; 2,691,622; 2,745,792; and 2,767,120. Theseprocesses are generally based upon the extraction of hydrocarbons withBF, complexes, the polymerization of unsaturates which remain insolution and can be removed by distillation of the BF,-treatedhydrocarbon, or the fonnation of partially soluble sludges ofnonhydrocarbons impurities by treating with BF, that are then extractedwith suitable solvents. In the case of heavy stocks or previouslyunrefined stocks it has been found that extraction with boron fluoridedoes not readily afford complete phase separation of the impurities fromthe refined hydrocarbon.

In accordance with the present invention, it has been discovered thathydrocarbon stocks may be advantageously refined by admixing a smallportion of a member selected from the group consisting of water andboron trifluoride monohydrate with said hydrocarbon stocks and thentreating said admixture with gaseous boron trifluoride thereby formingan insoluble precipitate of the undesirable impurities in thehydrocarbon stocks that can be readily separated from the refined stock.It is an essential feature of the present invention that the amount ofgaseous boron trifiuoride used is in excess of that stoichiometricallynecessary for complex formation with the water.

The process according to the present invention may be carried out oncrude petroleum hydrocarbon distillates, upon fractions producedtherefrom by distillation, upon crude petroleum stocks and artificialmixturesof petroleum fractions, on partly refined hydrocarbons or otheruntreated or treated hydrocarbons on byproducts obtained from therefining or dewaxing of petroleum fractions, or stocks obtained bycracking hydrocarbons and on coal tar and coal tar distillates. Thislist of products is illustrative only and other hydrocarbon stocks maybe effectively treated in accordance with the present invention.

1n practicing the process of the present invention small proportions ofwater is first thoroughly admixed with the hydrocarbon stock and gaseousboron trifluoride is then added to the admixture. Between about 0.1percent to about percent by weight and preferably between about 0.5percent and 1.5 percent by weight of water based on the hydrocarbonstock is admixed with the hydrocarbon stocks. Boron trifluoridemonohydrate is also suitable for use, preferably in amounts rangingbetween about 1.5 percent and 4 percent by weight based on thehydrocarbon stock.

The amount of gaseous BF, employed may vary within wide limits dependingon the type of hydrocarbon stock to be refined and the content ofundesirable constituents to be removed. It is essential when water isemployed that the amount of gaseous boron trifluoride used is greaterthan stoichiometrically necessary for complex formation with said water,an excess of between about percent and 50 percent by weight of gaseousBF, being advantageously employed. An amount of gaseous BF, rangingbetween about 2 percent and 5 percent by weight based on the hydrocarbonstock has been advantageously employed in combination with borontrilluoride monohydrate-hydrocarbon admixtures.

The process of the present invention may be carried out over a widerange of temperatures and pressures. Temperatures of from about 0 to 150C. have been found convenient for carrying out the refining process,while temperatures falling within the range of 60 to 120 C. areespecially suitable and preferred. The process may be carried out atatmospheric pressure, but higher pressures accelerate procedure and aregenerally preferred.

The treatment in accordance with the process of the present inventionremoves certain components by formation of compounds which areincompatible with the refined hydrocarbons, as for example, bypolymerization, complex formation, formation of highly polar compounds,coagulation of asphaltic compounds, etc. After the treatment two phasesare formed,

one phase consisting of the refined hydrocarbons and a second which iscomposed of the incompatible compounds, that may be readily separatedfrom each other by gravity settling or other known methods. It is animportant feature of the present invention that the undesirableconstituents are removed from the treated hydrocarbon by precipitation,a relatively simple and inexpensive technique, rather than by extractionor distillation.

The refined oil phase will contain only a very small percentage of borontrifiuoride that can be easily removed by distillation under a slightvacuum. The oil can then be used as a finished petroleum oil as such orcan be subjected to a finishing treatment, as for instance, treatmentwith activated clay or sulfuric acid, hydrogenation or any otherfinishing treatment. The result will be an improved product withsignificantly improved color, improved stability and with a reducedcontent of undesirable constituents.

The precipitated phase will contain most of the boron trifluoridetogether with the incompatible undesirable impurities and it is possibleto recover the boron trifluoride from the precipitate by distillation atappropriate temperatures with or without the application of a vacuum.

It has been discovered that particularly advantageous method forrecovering BF, from the precipitate is by the use of a falling filmevaporator to carry out the distillation recovery procedure. In thistechnique the precipitated phase flows in the form of a thin film downalong a tube heated to between 250 and 300 C. and the BF, is readilyrecovered. The recovered BF, is suitable for reuse in the refiningprocess, enabling the process to be carried out continuously usingrecycled BF,. The precipitate may be continuously supplied to the filmevaporator and recovered BF, and sludge residue continuously taken off.

The process of the present invention can be applied to petroleumdistillates'to improve the quality of heavy gas oil and light spindleoil and similar products originating from the atmospheric distillationof crude petroleum, but is also valuable for refining vacuum distillatesused for lubricating oils and for special applications such as fortransformer and electrical oils. It is also very effective for therefining of residual products.

The following examples are illustrative of the practices of the presentinvention'but are not to be considered as limitative of its scope.Percentages stated are by weight.

EXAMPLE I A reaction vessel, provided with stirring equipment, wasfilled with 500 grams of an unrefined cylinder oil (see specification intable 1, column 1). Y

The oil was heated to a temperature of C., and 3 grams (0.6 percent byweight) of water were added with agitation.

Gaseous boron trifluoride was introduced into the admixture of cylinderoil and water maintained at a temperature of about 90 C. until 15.5grams were absorbed. The reaction mixture was then allowed to separateinto an upper layer of refined oil and a lower layer consisting ofcompounds which were immiscible with the upper layer. Alter decanting,an upper layer weighing 455 grams and containing 0.12 grams BF, wasobtained. The immiscible lower layer had a weight of 63.3 grams.

The refined oil phase was heated to 200 C. under a vacuum of 30 mm. H,vacuum in order to separate the dissolved BF,. Thereafter the refinedoil was neutralized with lime and the refining treated during 30 minuteswith 5 percent of activated clay at a temperature of 120 C. The refinedoil fraction thereby obtained has the properties as set out in column 2of table I below.

The separated immiscible precipitate layer was distilled employing afalling film evaporator at a temperature of 250- 300 C. and atmosphericpressure. The BF;, present in this phase was substantially completelyrecovered and collected for reuse.

From the aforementioned figures it is apparent that the treatment asdescribed yields an oil with considerably improved .characteristics,with a yield before clay treatment of over 90 percent. A conventionalrefining method applied to the same cylinder oil, consisting of solventrefining with a selective solvent followed by acid treatment withsulfuric acid, neutralizing and clay treatment, will give a yield ofabout 70 percent refined oil, but with a color of only 5.5/6 ASTM.

EXAMPLE 2 3 grams of H,O were added with agitation to 500 grams of apartly refined bright stock oil (see specification in table II,

column I) in the reaction vessel described in example I. The

admixture was heated to a temperature of 90 C. and BF, was added until20 grams were absorbed.

The immiscible products were separated by centrifugation and a refinedoil phase of 377 grams was obtained, which contained 0.4 grams BF TableII Column l Column 2 Spec. Gravity 20/4'C. 0.890 0.880 Vise. cenlistokesH0" F. l03.4 90

Visc. centistoku 200' F. 30.3 27

Basic Nitrogen I: 0.0l2 0.00!

k Sulfur L28 0.6 Color ASTM Dl500 6 1.5

Color after aging 48 hour: at 120' C. dil. B 2.5

EXAMPLE 3 L5 grams H,O were added with agitation to 750 grams of a lightspindle distillate (see specification in column 1, table III) at atemperature of 60 C. in the same way as described in example 1.

BF, gas was added to the heated admixture until 21 grams of BF wereabsorbed. The immiscible phase was separated by gravity settling and 735grams of a refined oil were obtained, which contained 0.37 grams ofBF,,. The BF, was separated from this oil fraction by distillation asdescribed in example 1.

The oil was then neutralized by washing with lime and treated with 2percent activated clay for 30 mins. at 120 C.

The specification of the oil thereby obtained is stated in table lll,column 2. The original product (table lll, column 1) was treated with 5percent activated clay, to compare the result with the BF, treated oil.

Both oils were then stored at temperatures of 120 C. for 96 hrs. Afterstorage the oil not treated with BF, had a color of 4.5 ASTM Dl500,while the oil treated with BF; had a color of 1.5 ASTM D1500.

Color Lovibond 2" cell. 0.5 (Yellow series) EXAMPLE 4 500 grams of aselected light lubricating oil extract obtained from furfural extractionof a lubricating oil stock to which 0.63 percent by weight of water wasadded, was agitated for about 3 hours at C. During this time gaseous BF;was passed through the agitated extract. At the end of the treatment 5.3weight percent of BF;, gas was absorbed. After settling two layers wereobtained. The refined oil product and a sample of the starting furfuraLextract were clay treated with 6 percent by weight of an activated clay.The results of the treatment are listed below:

Light extract B Fg-Wfltel Clay and clay Untreated treated treated Yleld,percent 96 86 Vise. centlstokes 20 C 698 690 451 Vlsc. centlstokes 60 C31 30 25 Vise. centlstokes 100 C 7 7 6 Color ASTM D1500 Dll. L7.6 Dll.7.0 4. 0

EXAMPLE 5 Boron trifluoride monohydrate was admixed with a cylinder oilrafi'mate havinga specific gravity at 20 C. of 0.936, an NPA (NationalPetroleum Association) color of 8 and a viscosity of 664,v centistokesat 50 C. and said admixture was treated with BF; gas in the proportionsof ingredients described in the table below. Color properties of thetreated hydrocarbon is summarized in the accompanying table. Othersamples of the above described cylinder oil were separately 3 with BF,gas and BF l-l O and the comparative results are summarized below. Whenthe oil was treated with BF gas only no color improvement was noted.Refining with the combination of 3 percent BF H,O and 2 percent BF gasresulted in color properties comparable with 10 percent BF, H 0refining, indicating obvious economic advantages. All of the refiningprocedure of this example were carried out at 80 C.

BFgHzO BF: gas

Percent Percent Color after g ms Grams by wt. Grams by wt. Timetreatment 3 10. 7 2 4.5 hours 2% NPA An NPA color of 8 corresponds to adeep red color; NPA colors in the range of 4 to 2 correspond to orangepale, 4, to extra pale, 2. See W. L. Nelson, Petroleum RefineryEngineering, 4th Ed. (New York: McGrawl-lill Book Company, Inc., 1948),Chapter 3 for a comparison of commonly used petroleum color scales.

Other variations and modifications of the details of this invention willbe apparent to those skilled in the art within the scope of the appendedclaims.

What is claimed is:

1. A process for refining hydrocarbon stocks which comprises admixing asmall portion of water with the hydrocarbon stocks and then treatingsaid admixture with gaseous boron trifluoride, said gaseous borontrifluoride being added in an amount in excess of thatstoichiometrically necessary for complex formation with said water, toobtain an insoluble precipitate of undesirable constituents that can bereadily separated from the refined hydrocarbon.

2. A process according to claim 1 which is carried out at a 7temperature between about 0 and 150 C.

3. A process according to claim 1 wherein between about 0.1 percent and5 percent by weight of water based on the weight of hydrocarbon stock isadmixed with said hydrocarbon stock.

4. A process according to claim 3 which is carried out at a temperaturebetween about 60 and C.

5. A process according to claim 1 wherein an excess of between about 10percent and 50 percent by weight of gaseous BF over the amountstoichiometrically necessary for complex formation with said water isemployed.

6. A process according to claim 1 which includes recovering of saidboron trifluoride treating agent by distillation from said precipitatedand refined hydrocarbon phases.

7. A process according to claim 1 which includes recovering of saidboron trifluoride treating agent from the precipitated phase with afalling film evaporator.

0 i i i 0

2. A process according to claim 1 which is carried out at a temperaturebetween about 0* and 150* C.
 3. A process according to claim 1 whereinbetween about 0.1 percent and 5 percent by weight of water based on theweight of hydrocarbon stock is admixed with said hydrocarbon stock.
 4. Aprocess according to claim 3 which is carried out at a temperaturebetween about 60* and 120* C.
 5. A process according to claim 1 whereinan excess of between about 10 percent and 50 percent by weight ofgaseous BF3 over the amount stoichiometrically necessary for complexformation with said water is employed.
 6. A process according to claim 1which includes recovering of said boron trifluoride treating agent bydistillation from said precipitated and refined hydrocarbon phases.
 7. Aprocess according to claim 1 which includes recovering of said borontrifluoride treating agent from the precipitated phase with a fallingfilm evaporator.